This invention relates generally to coating apparatus, and more particularly to an adhesive particle trap applicator apparatus for depositing an adhesive in the troughs of the corrugated sheath of a compressed gas-insulated transmission line.
Compressed gas-insulated transmission lines are being increasingly utilized to transmit large magnitudes of electrical energy. Typical gas-insulated transmission lines include a cylindrical rigid outer sheath typically at ground potential and a high-voltage inner conductor disposed within the outer sheath. An insulating gas, such as sulfur hexachloride, is utilized inside the outer sheath to electrically insulate the inner conductor from the outer sheath. Insulating supports are utilized at spaced intervals along the length of the transmission line to insulatably support the inner conductor within the outer sheath. Particle traps, used to deactivate contamination particles within the line, are typically disposed at spaced intervals along the length of the transmission line.
One disadvantage with the typical gas-insulated transmission lines is that the lines themselves are rigid; they cannot be significantly bent or turned to accommodate changes in direction or to avoid unforeseen obstacles within their path. All changes of direction in a transmission line must therefore be typically accomplished through the use of elbows or junction boxes or the like. To overcome this drawback, a new type of gas-insulated transmission line is being investigated. The new type of transmission line utilizes a corrugated outer sheath and a flexible inner conductor which provide flexibility in the transmission line. This flexibility can then be utilized to facilitate changes of direction.
One obstacle to the manufacture of this new type semi-flexible gas-insulated transmission line concerns contamination particles which may be disposed within the outer sheath, and which may cause a premature breakdown of a transmission line. In the rigid outer sheath systems, particle traps were placed at spaced intervals along the length of the transmission line. Contamination particles present within the line, following an application of a lowered voltage, would tend to migrate longitudinally along the transmission line until they became trapped in the particle traps. They then were effectively prohibited from affecting operation of the transmission line. However, with the corrugated outer sheath of the new semiflexible transmission lines, the particles are unable to easily migrate the length of the lines. As a consequence, these particles are not readily trapped within the particle traps, and are thus free to cause premature breakdown of the system.
One method for immobilizing the contamination particles in the corrugated outer sheath is to utilize an adhesive material to physically capture the particles within the outer sheath and thus prevent them from obtaining the mobility to initiate breakdowns. The most desirable location to apply the adhesive in the troughs, or low spots, in the bottom portion of the transmission line, where the electric field is lower than on the crowns of the corrugations. Some apparatus must then be utilized to apply this adhesive only in the troughs of the corrugations of the outer sheath of the transmission line, and this apparatus must be capable of being utilized along the entire length of each corrugated outer sheath section, which may extend for 30 feet or more.